Identification and expression profile of the SMAX/SMXL family genes in chickpea and lentil provide important players of biotechnological interest involved in plant branching

Abstract

Main conclusion SMAX/SMXL family genes were successfully identified and characterized in the chickpea and lentil and gene expression data revealed several genes associated with the modulation of plant branching and powerful targets for use in transgenesis and genome editing. Abstract Strigolactones (SL) play essential roles in plant growth, rooting, development, and branching, and are associated with plant resilience to abiotic and biotic stress conditions. Likewise, karrikins (KAR) are “plant smoke-derived molecules” that act in a hormonal signaling pathway similar to SL playing an important role in seed germination and hairy root elongation. The SMAX/SMXL family genes are part of these two signaling pathways, in addition to some of these members acting in a still little known SL- and KAR-independent signaling pathway. To date, the identification and functional characterization of the SMAX/SMXL family genes has not been performed in the chickpea and lentil. In this study, nine SMAX/SMXL genes were systematically identified and characterized in the chickpea and lentil, and their expression profiles were explored under different unstressless or different stress conditions. After a comprehensive in silico characterization of the genes, promoters, proteins, and protein-protein interaction network, the expression profile for each gene was determined using a meta-analysis from the RNAseq datasets and complemented with real-time PCR analysis. The expression profiles of the SMAX/SMXL family genes were very dynamic in different chickpea and lentil organs, with some genes assuming a tissue-specific expression pattern. In addition, these genes were significantly modulated by different stress conditions, indicating that SMAX/SMXL genes, although working in three distinct signaling pathways, can act to modulate plant resilience. Most CaSMAX/SMXL and partner genes such as CaTiE1 and CaLAP1, have a positive correlation with the plant branching level, while most LcSMAX/SMXL genes were less correlated with the plant branching level. The SMXL6, SMXL7, SMXL8, TiE1, LAP1, BES1, and BRC1 genes were highlighted as powerful targets for use in transgenesis and genome editing aiming to develop chickpea and lentil cultivars with improved architecture. Therefore, this study presented a detailed characterization of the SMAX/SMXL genes in the chickpea and lentil, and provided new insights for further studies focused on each SMAX/SMXL gene.

Endogenous Hormone Levels and Transcriptomic Analysis Reveal the Mechanisms of Bulbil Initiation in Pinellia ternata

“…In Arabidopsis , overexpression of AtD27 -like1 in the d27 mutant effectively reinstated the phenotype of increased branching, thereby confirming the involvement of D27 in the biosynthesis of SL [ 58 ]. In a chickpea and lentil study, the majority of SMAX and partner genes were found to exhibit a positive association with the branching level of plants [ 59 ]. In this study, the expression of D27 was twofold lower in the DUs than in the SUs.…”

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“…In this study, two contrasting cultivars of chickpea and lentil were selected dealing with plant branching, according to a previous study carried out by Basso et al (2024a). The chickpea cultivars Blanco lechoso and FLIP07-318C were used as little and highly branched, respectively.…”

“…For this study, the chickpea cultivars Blanco lechoso (little branched) and FLIP07-318C (highly branched), and lentil cultivars Castellana (little branched) and Campisi (highly branched) were selected based on a previous study where the architecture/branching of these four cultivars was characterized and, among several cultivars, these four were considered most contrasting for this phenotype (Basso et al, 2024a). The cultivars Blanco lechoso and Castellana are characterized by presenting a low number of lateral branches and a dominant, well-defined, and semierect stem (Scarrone-type plant architecture; Halléand Oldeman, 1970).…”

“…The CCD subfamily genes (Basso et al, 2023) and SMAX/SMXL family genes (Basso et al, 2024a) of chickpea and lentil, both involved in carotenoids and dependent and independent strigolactones and karrikins pathways, were also exploited to evidence the strigolactones signaling modulation and eventual association with the branching phenotype. In particular, the CCD subfamily contains genes involved in the degradation of carotenoids for the production of strigolactones and other volatile and nonvolatile compounds, while chickpea and lentil SMAX1/SMXL1 genes are involved in the strigolactones and karrikins-dependent signaling pathway for regulation of shoot branching and hairy root elongation (Basso et al, 2023;Basso et al, 2024a).…”

“…Although knowledge of the genetic basis associated with different agronomically important traits of these two crops has been explored in recent years, little is known about the molecular mechanisms involved in the branching and architecture of chickpea and lentil. A recent study identified and characterized the expression profile of SMAX/SMXL family genes in the chickpea and lentil revealing several strigolactonesassociated genes with positive or negative correlations with the plant branching level (Basso et al, 2024a).…”